REGENERATION OF SCIRPUS-AMERICANUS IN A TEXAS COASTAL MARSH FOLLOWINGLESSER SNOW GOOSE HERBIVORY

Interaction of herbivory by wintering lesser snow geese (Anser caerule scens caerulescens), environmental conditions, and burning were invest igated in a mid-Texas coastal marsh dominated by Scirpus americanus (O lney bulrush). Goose grubbing and use of S. americanus rhizomes and ro ots initially produced a patchwork of denuded and vegetated areas on a recently burned area. Regrowth occurred by reestablishment of uproote d shoot complexes; regeneration from seed was not observed. Regrowth w as dependent on intensity of use and post-herbivory environmental cond itions. After three years of varying levels of goose use and environme ntal conditions, lowest foliar cover and standing crop occurred in are as with a high frequency and intensity of goose use followed by spring drought and high salinities. Greatest growth was associated with low frequency and intensity of use followed by normal spring freshwater in flows and low salinities. Burning did not significantly affect the res ponse of S. americanus. Continued frequent and intense snow goose use, coupled with high salinity and extended periods with water levels bel ow the marsh surface, can produce denuded mudflats subject to accelera ted soil erosion. Management strategies to reduce the impact of these combined events could be implemented. Hydroperiod and salinity conditi ons should be routinely monitored, and goose populations should be tem porally and spatially directed to reduce the potential for conversion of marsh to permanent mudflats.